Correlations with p-c(n)-T Relationships of Strain Gradient Dependent Hydrogen Diffusion in Pd₈₁Pt₁₉H _n Membranes

Stress induced changes in hydrogen pressure in contact with tubular diffusion membrane

“…The hydrogen diffusion was commenced by introducing hydrogen to the outer surface of the tube membrane either by electrolysis (Lewis et al, 1987, Kandasamy et al, 1991 or gas phase adsorption (Kandasamy et al, 1990). The pressure changed inside the tubular membrane were recorded by a pressure gauge.…”

Numerical simulation of diffusivity of hydrogen in thin tubular metallic membranes affected by self-stresses

“…where E is the Young's modulus, E =100-200 GPa; is the Poisson's ratio, = 0:3-0.4; C0 is the concentration of H in M corresponding to nH = 1, C0 = 0:1-0:15 mol H cm −3 for materials used experimentally [1,2,[13][14][15][16][17][18][19][20][21][22][23][24][25][26]; L is the membrane thickness; z is the coordinate along the thickness direction, the upstream side is z = 0 (outer surface) and the downstream side is z = L (inner surface). The hydrogen ux has the form…”

“…(8) is appropriate with H 2 =2 being replaced by the chemical potential of hydrogen adsorbed on the outer surface. For the galvanostatic charging as used experimentally [1,2,[13][14][15][16], the corresponding boundary condition is…”

“…In experiments, the applicability of time characteristics is determined by the techniques employed. For gas/membrane/gas and electrolyte/membrane/gas situations, L is easily acquired by the measurement of pressure change; therefore, the time-lag method has been used widely [1,2,[13][14][15][16][17][18][19][20][21][22][23][24]. If an electrolyte is introduced in the tube [16], L can be estimated from the potential change and 1=2 can be evaluated from the anodic current, which re ects the di used ux.…”

“…The UHD phenomena, the time courses of pressure change in a tube during hydrogen absorption and interruption of steady di usion [1,2,[13][14][15][16][17][18][19][20][21][22][23][24] were demonstrated and interpreted by these theories. Besides these phenomena, it has been found that self-stresses lead to changes of apparent di usion coe cient (ADC) if traditional relations are applied in experiments [1,2,[13][14][15][16][17][18][19][20][21][22][23][24][25][26]. This is one of the reasons that ADCs of H in metal (alloy) hydrides di er from one work to another.…”